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Histopathology > Lower GI disease > Flashcards

Lower GI disease Flashcards

1
Q

Examples of congenital disorders affecting the large bowel

A
  1. atresia/stenosis
  2. hirschsprung’s
  3. duplication
  4. imperforate anus

most common hirschsprung’s

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2
Q

What is the congenital abnormality in hirschsprung’s disease?

A

absence of ganglionic cells in the myenteric plexus

causes failure of dilatation of the distal colon

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3
Q

Which patient group does hirshcsprung’s affect?

A

80% affects male babies

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4
Q

Presentation of hirschsprung’s disease

A

constipation with overflow diarrhoea

abdominal distension

vomiting

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5
Q

Associations of hirschsprung’s disease

A
  1. down’s syndrome
  2. RET proto-oncogene
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6
Q

Diagnosis of hirschsprung’s disease

A

full thickness biopsy

hypertrophy of nerve cells but absence of ganglion cells

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7
Q

Treatment of hirschsprung’s disease

A

Resection of affected (constricted) segment

Ano-rectal pull through

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8
Q

Which parts of the bowel are affected by volvulus? (small intestine vs large intestine)

A

Children: small intestine: Midgut volvulus

Elderly and pregnant women: sigmoid colon (sigmoid > caecal)

*think children are younger; more proximal part is affected

  • NOTE: psychiatric patients also get this (?medication related)
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9
Q

3 types of volvulus

A
  1. caecal
  2. midgut
  3. sigmoid
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10
Q

AXR findings of sigmoid vs caecal volvulus

A

sigmoid: coffee bean sign
caecal: embryo sign

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11
Q

Associated factors for diverticular disease

A

Age (>60 years)

Chronic Constipation

Diet:

Low Fibre

Rich in fatty food or red meat

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12
Q

Difference between pseudodiverticulum and true diverticulum

A

pseudodiverticulum: caused by high intraluminal pressure eg due to straining –> causes outpouchings. does not involve all layers of the bowel wall

true diverticulum: caused by traction/pulling forces –> involves all layers of the bowel wall

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13
Q

Which side of the colon is most affected by diverticular disease?

A

90% are left sided

**maybe because constipation commonly causes faecal impaction on the left side??

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14
Q

Diagnosis of diverticular disease

A

CT with contrast

colonoscopy is contraindicated in acute diverticulitis due to risk of perforation

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15
Q

Which drugs can cause c diff colitis?

A

4Cs:

cephalosporins

ciprofloxacin

clindamycin

co-amoxiclav

can also be precipitated by antacids/PPIs, cytotoxic drugs and non-surgical procedures eg NG tubes

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16
Q

Histological appearance of c difficile colitis

A

pseudomembraneous colitis

looks like volcano exploding - bits on the surface are necrotic pseudomembranous regions full of pus and inflammatory cells

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17
Q

CRP in C difficile colitis

A

CRP may be low

even though WCC is high

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18
Q

C difficile treatment

A
  1. moderate severity: metronidazole –> vancomycin if no response
  2. severe: vancomycin first, can add on metronidazole
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19
Q

Which ribotype of c difficile is associated with increased toxicity?

A

Ribotype 027

caused an outbreak in June 2005

as it produces more toxins

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20
Q

Which genetic mutation can predispose to crohn’s?

A

NOD2 mutation

present in 30% of people with crohn’s

**NOD2 is expressed in myeloid cells

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21
Q

Characteristic features of crohn’s disease

A

Crow’s NESTS

N: no blood or mucous

E: entire GI tract can be affected (most common in terminal ileum and large bowel- caecum)

S: skip lesions

T: transmural inflammation

S: smoking is a risk factor

Histological features:

  • non-caseating granulomas
  • rose thorn ulcers
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22
Q

Management of Crohn’s disease

A

Inducing remission:

1st line: corticosteroids (PO–>IV)

2nd line: immunosuppressants

Maintaining remission:

immunosuppressants

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23
Q

Which is more common: crohn’s or UC?

A

UC is slightly more common

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24
Q

Key features of ulcerative colilitis

A
  • Extends proximally from rectum
  • Continuous inflammation
  • Inflammation confined to the mucosa → bowel wall is normal thickness
  • Usually does not affect the small intestine unless severe pancolitis causes backwash ileitis
  • Extensive superficial broad ulcers
  • No granulomas/ fissures/ fistulae/ strictures
  • Islands of regenerating mucosa bulge into lumen → pseudopolyps
    • can fuse to form mucosal bridges
  • May see appendiceal involvement
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25
Q

Extraintestinal manifestations of ulcerative colitis

A

Arthritis

Myositis

Uveitis/ iritis

Erythema nodosum

pyoderma gangrenosum

Primary sclerosing cholangitis

**pretty much the same as crohn’s disease except PSC

26
Q

Management of ulcerative colitis

A

Inducing remission:

1) Mild:

  • prednisolone
  • mesalazine (5-ASA)

2) Moderate:

  • prednisolone
  • 5-ASA mesalazine
  • steroid enema bd

3) Severe:

  • Admit
  • NBM
  • IV fluids
  • IV hydrocortisone
  • rectal steroids
  • Maintain remission:
  • 1st line: 5-ASA - mesalazine
  • 2nd line: azathioprine

Maintain remission

  • 5-ASA
  • immunosuppressants
27
Q

What is the most common vascular disorder of the GI tract?

A

Ischaemic colitis/ifarction

**can be acute or chronic

28
Q

Where do diverticulae usually form?

A

At points where nutrient arteries penetrate the GI tract

–> taenia coli

29
Q

Which areas of the bowel does ischaemic colitis affect?

A

Watershed areas - receive dual blood supply.

a) rectosigmoid
b) splenic flexure

30
Q

Small bowel vs large bowel ischaemia

A
31
Q

Histological findings of ischaemic colitis

A
  • thickening of bowel wall
  • necrotic ulceration confined to mucosal layers
32
Q

Types of non-neoplastic polyps in. the bowel

A
  1. hyperplastic
    - most common
    - rectosigmoid
    - rare- malignant potential
  2. hamartomous
    - isolated or as part of syndromes eg peutz-jeghers, juvenile
  3. inflammatory
    - associated with inflammatory bowel disease
    - aka pseudopolyps (ulcerative colitis)
33
Q
A
34
Q

Definition of adenoma

A

Excess epithelial proliferation with dysplasia

35
Q

3 types of adenoma

A
  1. tubular
    - lowest malignant potential
  2. villous
    - highest malignant potential

(V for violent)

  1. tubulovillous
    - intermediate malignant potential
36
Q

Description of villous adenoma

A

sessile cauliflower-like mass covered by dysplastic columnar epithelium in the rectum

37
Q

Risk factors for adenoma progressing to cancer

A
  1. size
  2. villous content
  3. degree of dysplastic changes
38
Q

Adenoma carcinoma sequence

A
39
Q

What electrolyte abnormality may be seen in colorectal adenoma?

A

hypokalaemia

**because the adenoma leaks potassium

**also causes hypoproteinaemia

40
Q

Which area of the bowel is most commonly affected by adenocarcinoma?

A

rectosigmoid

41
Q

Left vs right colon cancer presentation

A

left: obstruction
right: anaemia

42
Q

What staging is used for colorectal adenocarcinoma?

A

Duke’s staging

A = confined to bowel wall

B = through bowel wall

C = lymph node metastases

D = distant metastases

43
Q

Name 3 familial syndromes characterised by intestinal polyps

A
  1. peutz jeghers
  2. HNPCC
  3. FAP
44
Q

Which type of polyps in peutz jegher’s?

A

Hamartomous polyps

45
Q

Which genes are mutated in HNPCC? Mode of inheritance?

A

MSH2 and MLH1

Autosomal dominant

rare

46
Q

Where do you get tumours in HNPCC? Type?

A

Proximal to splenic flexure

Tend to be mucinous adenocarcinomas

47
Q

Which other type of tumour does HNPCC predispose to?

A

Ovarian tumours

–>endometroid and mucinous (think mucinous - tend to form mucinous tumours in the GIT also)

(early onset- more bc of HNPCC than BRCA)

48
Q
A
49
Q

Mode of inheritance of FAP

Which gene is affected?

A

autosomal dominant

Mutation in APC tumour suppressor gene on chromosome 5q21

50
Q

Two forms of FAP

A
  1. Gardener’s
    * bony and soft tissue tumours
  2. Turcots
  • gliomas
  • medulloblastoma
51
Q

Between crohn’s and UC which one has higher monozygotic twin concordancy?

A

Crohns: 50%

52
Q

Which cells does carcinoid syndrome originate from?

A

Enterochromaffin cells

produce 5-HT (serotonin)

53
Q

Where do carcinoid tumours arise from?

A

Commonly in bowel

but also lung, ovaries and testes

54
Q

Carcinoid syndrome vs carcinoid crisis

A
55
Q

Ivx and treatment of carcinoid tumours

A

Investigation: 24hr urine 5-HIAA (main metabolite of serotonin) Treatment: Octreotide (somatostatin analogue

56
Q

Juvenile vs peut-jeghers syndrome

A
57
Q

2nd commonest cause of cancer deaths in UK

A

colorectal cancer

58
Q

What drug is protective against colorectal cancer?

A

NSAIDS - as a lot of tumours express COX-2

59
Q

Tumour marker of colorectal carcinoma

A

Carcinoembryonic antigen

60
Q

What is gardner’s syndrome?

A

– like FAP with extra intestinal features eg: osteoma’s, dental caries

61
Q

complciations of diverticular disease

A
  • Pain
  • Diverticulitis
  • Perforation >>> peritonitis
  • Fistula (bowel, bladder, vagina)
  • Obstruction

Histopathology (18 decks)

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